Animals
All experiments were conducted in accordance with the guidelines of the Institutional Animal Care and Use Committee at Princeton University and the guidelines and policies of the United States Department of Agriculture, as required by the Animal Welfare Act. Subjects included laboratory-bred African striped mice (R. pumilio), which originated through systematic outbreeding in a captive colony at Princeton University (obtained through Harvard University, in turn obtained through the University of Zurich) and originating from Goegap Nature Reserve, South Africa (29° 41.56′ S, 18° 1.60′ E). No wild animals were used in this study, and no samples were collected from the field. Striped mice were maintained in a temperature-controlled (22.2 °C or 72 °F) and humidity-controlled (40–55%) vivarium on a 12/12 light/dark cycle (lights ON at 07:00; lights OFF at 19:00) with water ad libidum. Standard rodent chow (LabDiet 5053, PicoLab Rodent Diet 20) was restricted to 4 g per mouse per day to prevent the onset of obesity. Sunflower seeds (roughly ten seeds per mouse) were also provided as a form of enrichment. All striped mice were housed in large polycarbonate rat cages (30.80 cm × 59.37 cm × 22.86 cm, Thoren) with a corncob and cotton-mixed bedding with a small volume of shaved aspen and sterile cotton squares for extra nesting material. Further enrichment in the home cage included a translucent red plastic tube and a plastic running wheel. Sexually naive striped mice were housed between one and five per cage. Breeding animals (including dams and sires) were pair-housed with mates and pups under the conditions described above. Sex was assigned as male or female according to visual inspection of externalized genitalia and anogenital distance at weaning on postnatal day (PND) 20 and confirmed in adulthood (at PND90 or above) with the presence or absence of testes.
Statistics and reproducibility
Statistical software
Analyses were completed in R49 (v.4.4.1) and GraphPad Prism (v.9.4.1). For all inferential statistics, a threshold of P ≤ 0.05 was used to determine significance. More methods regarding statistical analysis can be found in the Supplementary Information.
Power analysis
Power analysis for initial paternal behaviour testing used the pwr.anova.test function (R, pwr package). Initial parameters (power 0.80, Cohen’s f = 0.585) were based on published paternal behaviour studies28 and calculated to need n = 12.5. Parameters were then adjusted based on our own first cohort (n = 47: 24 SI, 23 GH, new Cohen’s f = 0.606, target power 0.80), and calculated to need n = 11.7 mice per group in a two-way comparison and 9.8 mice per group in a three-way comparison.
Reproducibility
All representative micrographs were replicated independently with similar results two or more times. This includes micrographs demonstrated in Figs. 3k,l and 4b–e,g,h and Extended Data Figs. 8c,d and 9e–g.
GH and SI
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